code: def helper(self, input):
      gen = VectorInput(input)
      accu = RealAccumulator()
      derivativeSfx = sDerivativeSfx()
      p = Pool()
  
      gen.data >> accu.data
      accu.array >> derivativeSfx.envelope
      derivativeSfx.derAvAfterMax >> (p, "sfx.derAvAfterMax")
      derivativeSfx.maxDerBeforeMax >> (p, "sfx.maxDerBeforeMax")
  
      run(gen)
  
      return (p["sfx.derAvAfterMax"][0], p["sfx.maxDerBeforeMax"][0])
  
file_path: essentia/test/src/unittests/sfx/test_derivativesfx_streaming.py
imports: from essentia_test import *
  from essentia.streaming import DerivativeSFX
label_desc: Use image node_id 1 for calling the TestDerivativeSfx_Streaming obj's underlying member method code with example usage: obj.helper(input) and returns: p,  p